Dynamic response of physisorbed hydrogen molecules on lanthanide-modified zirconia nanoparticles

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Ultrafine lanthanide (Ln = Ce and Nd)-modified zirconia powders synthesized by a coprecipitation method exhibit high surface areas and adsorption sites that are essential for catalytic applications. We report a study of the surface chemistry of Ce{sub 0.1}Zr{sub 0.9}O{sub 2} and Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95} powders. First, the specific surface area and porosity are characterized by nitrogen isotherm-adsorption measurements. Second, the motion of hydrogen molecules physisorbed on Ce- and Nd-doped zirconias is studied by inelastic neutron scattering. Nitrogen adsorption-desorption isotherm measurements yield a BET surface area (26.1 m{sup 2}/g) and mesopore size ({approximately}5 nm radius) in Ce{sub 0.1}Zr{sub 0.9}O{sub 2} ... continued below

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6 p.

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Loong, C.K.; Trouw, F.; Ozawa, Masakuni & Suzuki, Suguru October 1, 1997.

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Ultrafine lanthanide (Ln = Ce and Nd)-modified zirconia powders synthesized by a coprecipitation method exhibit high surface areas and adsorption sites that are essential for catalytic applications. We report a study of the surface chemistry of Ce{sub 0.1}Zr{sub 0.9}O{sub 2} and Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95} powders. First, the specific surface area and porosity are characterized by nitrogen isotherm-adsorption measurements. Second, the motion of hydrogen molecules physisorbed on Ce- and Nd-doped zirconias is studied by inelastic neutron scattering. Nitrogen adsorption-desorption isotherm measurements yield a BET surface area (26.1 m{sup 2}/g) and mesopore size ({approximately}5 nm radius) in Ce{sub 0.1}Zr{sub 0.9}O{sub 2} as compared to those (72.3 m{sup 2}/g and {approximately}3 nm) in Nd{sub 0.1}Zr{sub 0.9} O{sub 1.95}. The vibrational densities of states of H{sub 2} on Ce{sub 0.1}Zr{sub 0.9}O{sub 2} and Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95} were measured at 20 K over the 0-200 meV energy range for three hydrogen coverage. The spectra for both samples consist of two parts: a sharp peak at {approximately}14.5 meV and a broad component extending beyond 200 meV. The sharp peak corresponds to transitions from the J=0 to J=1 rotational states of bulk hydrogen molecules, and its intensity decreases with decreasing H{sub 2} coverage. The broad component corresponds to overdamped motion of surface adsorbed hydrogen molecules. The major difference in the latter component between the Ce- and Nd-doped samples is an excess of intensities in the 5-14 meV region in Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95}. The confined motion of adsorbed H{sub 2} on the different micropore and mesopore surfaces of Ce{sub 0.1}Zr{sub 0.9}O{sub 2} and Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95} is discussed.

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6 p.

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INIS; OSTI as DE98050019

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  • ICNS `97: satellite conference, Argonne, IL (United States), 25-26 Aug 1997

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  • Other: DE98050019
  • Report No.: ANL/ER/CP--94630
  • Report No.: CONF-970893--
  • Grant Number: W-31-109-ENG-38
  • Office of Scientific & Technical Information Report Number: 565560
  • Archival Resource Key: ark:/67531/metadc698482

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  • October 1, 1997

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  • Aug. 14, 2015, 8:43 a.m.

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  • Dec. 15, 2015, 12:12 p.m.

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Loong, C.K.; Trouw, F.; Ozawa, Masakuni & Suzuki, Suguru. Dynamic response of physisorbed hydrogen molecules on lanthanide-modified zirconia nanoparticles, article, October 1, 1997; Illinois. (digital.library.unt.edu/ark:/67531/metadc698482/: accessed August 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.